OK to use non-oxygen barrier pex for heating?

Ken_40

I always thought PEX stood for polyethylene (PE) that is cross-linked (X) - meaning WITH an oxygen barrier.

Regular PE (simply "un"-crosslinked) polyethylene, has no oxygen barrier.

Remember, PEX does NOT mean no O2 can pass thru, only that the O2 "issue" is reduced by 98%. Oxygen still gets thru, especially if the outside of the brand/method of PEX purchased is the "barrier" aspect - and when you drag it thru floor joists, wall studs holes, etc., you may lose an additional 2 to 5% of the "barrier" anyhow. These kinds of percentages offer no major threat, at least that we know of - yet.

Non-ferrous HX's DO allow well designed systems to use PE. However, we find the cost of even a cheap HX is greater than the minimal added cost for cross linked PE and so, the debate becomes financially moot. PEX is about the same price as PE - with a HX included.

I suspect ME is correct, and when the lawyers get done, the code officials and authors will suddenly see the light.

Not because they actually see any light - simply that the headline news of judges granting 5-figure damage awards to litigants whose boilers crapped out makes them appear like they contributed to the problem, instead of doing anything resembling "prevention."

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HT in Pa_3

OK to use non-oxygen barrier pex for heating?

Some installers are using plumbing pex(non-oxygen barrier) tubing for hot water heating systems. I'm concerned that in time, it might do damage to the cast iron boiler, but I'm told they havn't had any problems. One company has been using plumbing pex for 25 years. Any of you have any input on this? Thank You. HT

Unknown

higher temperature water encourages more oxygen diffusion. Also if you're going to glycol, it will break down the inhibitors in it faster if you're open to oxygen.

low temp systems in concrete, you could probably make a case that you're ok, but generally speaking I would always use an o2 barrier. That's not a place I want to be "living on the edge".

[Deleted User]

In a word....

NO...

And hopefully, in the near future, after a few well placed people get the living crap sued out of them, it will become illegal, and against code to do so.

Little birdies whispering in my ear....

ME

hot_rod

will it work? or should you do it?

Check the listings on the tube in question first. Some manufacturers have been changing some of the listings they pay for on the tube. Plumbing, potable water pex, may not have the listing your AHJ requires.

Also you would need all non ferrous components. Boiler, circs, expansion vessel, air purger, etc.

Often when you pencil out the cost difference, considering all bronze or stainless components, the price difference for the hassle factor points to barrier tube.

Also if in the future upgrades are needed the owner is tied into all non ferrous repair or replacement parts.

hot rod

ALH_4

Oxygen Barrier

As I understand it, the crosslinking adds strength and temperature ressitance to the tube.

The oxygen barrier is either applied on the outside of the tube as an EVOH (etylene vinyl alcohol copolymer) layer, or as aluminum sandwiched between layers of PEx (PEx-Al-PEx).

PEx-Al-PEx should have better oxygen barrier properties than EVOH, which simply slows the diffusion of oxygen. Though both methods are very adequate.

Whether non-barrier tube makes sense is based on an economic anaylsis. Generally large slabs are better candidates for non-barrier tube than a home with hot water baseboard for example.

Jerry_15

Most boiler co's simply void the warranty for non-oxy tube. Not as deadly as the old poly-pro, but why would anyone waste their time for a few extra pennies. It's a wonderment to me that they still sell it, and guys still buy it. The luxury of pex is having a big old roll that works for everything, and has no waste. Good luck.

HT in Pa_3

Thanks for all the comments about O2 barrier and pex. I'm having a hard time finding a supplier that sells 1" or larger pex with o2 barrier. Who sells this. Should I consider pex-al-pex? Thx. HT

Chris_82

You might think about hiring someone that has done this sort of thing before, we are only going to go so far with someone, no disrespect, a diy, that dosent have a clue and can endangen himself and his family.

JOE_99

I would only use oxygen barrier

I installed 300 ft of PEX radiant heat(100 ft in concert,200 under floor boards).I was told (by more than one board +company I brought from,I didn't need oxygen barrier) because I'm using domestic hot water heater as a boiler I didn't need the oxygen barrier.The system works great but after 5 years running I have replaced 7 EXPANSION TANKS.I even tried to put some anti-freeze in to reduce the rust factor but that didn't help.They rusted from inside out.I'm getting a plastic lined one this year.

Joannie_12

One Inch??

Why do you need 1" or larger tubing?

Tom Hopkins

This will help!

Raw water in non-barrier PE will eat everything ferrous however, Changing the pH of the water will have extreme results. Raising the water to extremely alkaline (at or above 9.0) will reduce corrosion immensely!

Clean the entire system with TSP, then rinse. Then, put soda ash, caustic soda, or equally alkaline cheap and basically safe chemical "treatment" in the system. Test with an inexpensive pH water test kit, and stay between 9 and 10 pH levels.

Monitor the pH for a week or two. If it "wanders," keep monitoring weekly and adding the alkalai until the 9-10 pH levels stabilize. Then check every six months, minimally annually.

You'll find Expansion tanks lasting a lot longer, probably five to ten years - at least!

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scott markle_2

crosslinking

Ken, I believe your mistaken about non barrier pex not being crosslinked. The crosslinking creates physical properties that such as strength at high temperature that are not present in plain pe. Black well pipe is pe.

Tom Hopkins

You could be right!

But there's plenty of info available out there.

This may confuse or help(;-o)

http://www.ppfahome.org/pex/index.html

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Jerry_15

If you use non barrier you have to use a potable expansion tank. Don't forget to drop the tank pressure down from the factory pre-charge (60 PSI) to your operating system pressure or your relief valve will blow. Again, why anyone bothers to buy it or sell it is beyond my comprehension. It will go the way of poly pipe whithin 5 years just for inventory purposes alone.

Tom Hopkins

Jerry...

Thanks for the idea! I never thought about using a potable water expansion tank for non barrier tubing/system! Why not?

Like you, I wouldn't bother with non barrier for any app. I completely agree regarding the difference in barrier and non-barrier PE(X) pricing. In my house it was under 2-cents a foot difference. Maybe less. The more you buy, the cheaper the per foot costs.

I learn something every day here.

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Jerry_15

Ken

I'm using them more and more on any old nasty or questionable systems. They cost a whole 10 bucks more, and the customer pays for it. No call backs during the warranty time. No brainer. Oh yeah, don't forget you have to use a bronze or stainless circulator. Now how much money did you save on the tubing?